I’ve got about 70k on my truck now and think it’s time to replace the oxygen sensor(s), but I have some questions. How many do I have on my truck? Where are they? Do you have to have a special tool? And what kind of mileage gains could I expect? Also what brand should I get? Thanks

 

well i just got fone with ur same problem. i had no clue how to do it what i need etc. the FRONT o2's are the only ones u need to change. there are 2 front and 2 back... front ones actually are read by the computer and change air fuel. the back ones are just there to make sure your converters are working... i bought to bosch (OEM) o2's and a 22mm wrench (sears) like 5 bucks. run the truck and let it warm up... spray a little liquid wrench or something to loosen the rust off them (they are located with after the manifolds on yours engine and before your cats. shut off your truck and disconnect the battery. then crawl under ( i jacked it up a little bit just so it was easier to get under) and loosen the two o2's sensors... then i went inside had a few beers and waited for my exhaust to completely cool down. went back out and i unscrewed the rent of the sensor ... then you have to disconnect them from the little wiring harness ( pain in the ***) the drivers side was no biggy kinda get at it from the wheel well. the passanger side to be honest i almost gave up... wrenchs were flying and after a big dent in the fourwheeler from the hammer i had around i was curious to see if i could pull the harness up a little threw the engine bay. well you cant... its hooked on to a hanger behind the engine block BUT if you lay in there.. ontop of the plastic over the rad. you can reach one hand behind the engine and unhook it.. ( it took me 30 an hour the first time just to unhook it... then another 45 min to hook it back up when i got the new o2 installed... turned out the new one was bad so i had to take it out which was only 10 min and getting another new one took 5 min so you learn where to get your hand!) but back to changing... once both are out go get the new ones. make sure they have the anti seize crap on the threads... all new ones should. screw them in the holes and be carefull not to hit it on anything... they break very easy.try not to touch the bottom (part that goes in exhaust) because oil grease dirt and so on contaminates it and u need a new one....agian. once you screw them in... (very tricky on pass side again wiring harness for it gets caught on everything when it spins with the o2) hook up the harness. the drivers side like before is pretty easy to do once it is hooked up tighten a little (DONT over tighten) with the 22mm. the passenger side i managed to feed the harness up to the other end then go in to the engine bay and reach around again.if you have smaller or skiny hands you can get one over your valve covers and another threw an area by your tranny oil dipstick. its a time consuming job jsut have to figureout what you can and cant reach. if your need any help or pics or anything just let me know !! Motocross_areal_sport@hotmail.com GOOD LUCK

 

oh i forgot to add.. my truck has 72k and i had higher idle ( around 1200) i cleaned the throttle body and iac did a fuel filter change and put in fresh 0w-20 mobile one.. nothign helped... now it idles great! i dont kno about mpg im still on my first tank but so far the gauge is going down as fast flat out hp is differant but cruising up a small grade on the higway that normally either downshifts or slowly loses speed is great. i can slowly accelerate now up it which is better then hitting 3rd gear

 

The pass. side sensor is indeed a PITA.

You can only turn it fractionally at a time, so it takes a while to thread/unthread.

When you put the new one in, it will help if you tie the wire harness together into a bundle. Otherwise half your energy will be spent untwisting the wires as you thread the new sensor in.

 

i wish i woulda thought of that

 

Thanks guys for the tips. Anyone know the cheapest place to order some bosch 02's. They have them on ebay right now for $37 each. But I was looking to get them from a place with more reputation.

 

got mine at napa i think it came to 102 after tax and everything... that was for a set of 2 and some liquid wrench spray

 

Pepboys sell Bosch ones for about $50 each.

 

I got mine here:
http://www.oxygensensorwholesale.com/

Paid about $45/each including shipping, if I recall correctly.

 

So these things are considered standard maintenence items now? Change your O2 sensors like oil filter (except higher mileage)?

here I am with 98K on a '97 5.4 with original O2 sensors.....

 

you dont HAVE to change them out until they go bad... it wont hurt the motor if their working .. on the other hand the older they get (when their working) the slower they react. which means it takes time to compensate for a differant burn, changing them out may mean more mgp and better throttle response

 

how different is it with a 4.6l?

 

from what i saw under my friend 4.6 sport its exactly the same i think they use the same o2's even (dont quote me on that tho)

 

I am thinking of doing the same with my 91 5.0, is this easier to do on my truck than a newer one? Are the o2 sensors the same? I just put dual exhaust on my truck and would like to change them out if i can since i just replaced the exhaust.

 

yours would be easier.. you have odb 1 i believe which means you have 2 sensors total ( or maybe even one) im not sure but just open the hood... check on the exhaust manifold to see if there are any there and then crawl under the truck and look in front of the cats to see how many. your should see them in either place... as far as changing them... they HAVE ti be easier then my 2000